Osyraa attacks Book's home planet and the Discovery travels there to help. Stamets and Adira investigate The Burn.

After months spent reconnecting the Federation with distant worlds, Captain Michael Burnham and the crew of the U.S.S. Discovery are sent to assist a damaged space station – a seemingly routine mission that reveals the existence of a terrifying new threat.

Saru returns to help the U.S.S. Discovery uncover the mystery of an unusually destructive new force. As Burnham leads the crew, she must also find a way to help Book cope with an unimaginable loss.

Burnham and Tilly hunt the killer of a Starfleet officer as Stamets and the science team race against the clock to prevent the anomaly from killing anyone else.